Forsyth Specialized Caries Center has taken as its mission the The comprehensive investigation of the problem of root surface caries (RSC). At inception, information on RSC was relatively scant so it was appropriate to pose questions which were basic and general. For the continuation phase there will be a transition from the general to the specific and the focus will become more refined. A major objective will be to develop a comprehensive picture of the microbial populations associated with caries lesions by utilizing predominant cultivable flora techniques. In related ultrastructural studies, sections of extracted carious teeth will be means of specific labelled antisera. By similar means, a determination will be made of the identity and distribution of specific organisms in sections of extracted carious teeth. In a series of immunological studies, a determination will be made of the effect of pre- existent levels of GCF IgG antibody to suspected root caries-associated bacteria on the adherence and subsequent accumulation of indigenous A. viscous and mutans streptococci at tooth sites after plaque removal. The effect of pre-existent levels of salivary IgA antibody upon the recolonization of these organisms will also be studied. Additionally, it will be determined whether deep scaling elevates IgG antibody to these antigens and if so, a comparison will be made of recolonization in scaled and non-scaled subjects. The ongoing longitudinal study of immunological actors associated with changes in disease status will be continued,. The intrinsic properties of dentine vis a vis enamel will be compared by way of equilibration studies of the two minerals under partial pressures of CO2 and in vitro demineralization studies. A comprehensive characterization of the composition of plaque fluids associated with sound vs. carious sites will also be carried out. In the continuation of the bacterial adhesion studies, the novel proteins found in the mucin fraction of saliva which promote the attachment of Streptococcus mutans will be characterized. Further, the mechanisms by which the salivary acidic proline-rich proteins promote adhesion of specific bacteria to HA will be elucidated. Moreover, a determination will be made of the ability of selected bacteria to bind to dentine matrix components. The objective will be to investigate interactions between selected bacteria and dentine proteins using several approaches appropriate for each component isolated.